Studies are proposed to investigate the relationships between gonadal hormones and behavior. Questions are asked about which hormones and their metabolites are active, which neural systems are involved and about the mechanisms by which hormones act. Specifically questions are asked about the differentiating and activating effects of gonadal hormones in hamsters, about the role of androgen metabolism in the brain of the rat and about the role hormone controlled protein synthesis may be involved in the regulation of reproductive processes and sexual behavior.